Method and apparatus for imparting directional magnetic properties to core samples



P. `H. JONES "Aug, y11, 1942.

. METHOD AND APPARATUS FOR IMPARTING DIRECTIONA MAGNETIC PROPERTIES TO CORE SAMPLES 6. 1958 Filed Dec.

Q.C a www?? m wie P. 8 nl am F W MQQWDM E g Y, Z'.

WEA/mn y n Y .Jones Amm/EY.

Phi/1p H' BY Patented Aug. 11,1942 l. v

METHOD AND APPARATUS Foa IMPARTING nntEoTroNAL MAGNETIC PROPERTIES To CORE SAMPLES Philip H. Jones, Redondo Beach, Calif., assignor to' Union Oil Company of California, Los Angeles, Calif., a corporation of California.

Application netonnetv 6, 193s, serial No. 244,231 comme.v t (ol. g55-1.4)

This invention relates to core drilling and particularly to the determination oi' the orientation of drilled earth formation core samples such as that, for example, obtained in oil well drilling practice. t

The successful orientation-of core samples by magnetic polar determinations has been dependent upon the presence of sumcient natural magnetic material in the cored formation to impart anisotropic susceptibility or magnetic polarization to the core samplesrecovered therefrom.

Many such cored formations are found to contain suiiicient connate magnetic material to exmbit definite ond easily detectable anisotropic` magnetic properties and this vanisotropy is believed to havebeen originally established by the 'orienting edect of the presence of the terrestrial magnetic feld during the sedimentation or preclpitationof the magnetic particles comprising the subsequently consolidated formation, or to be the later result of the magnetizing iniiuence 4of the terrestrial magnetic iield acting upon the magnetic particles already present within the formation over long geologic periods of time.

Some ici-mation core samples, however, ex'

I artiiicially impart increased magnetic anisotropy to the portions of the formations to be cored whereby' magnetic polar orientation determinations of cored formation samples otherwise having insumclent natural magnetic properties can besuccessfully determined and whereby such `determinations of all cored samples whether possessing sumcient natural magnetic anisotropy or not can be greatly facilitated.

The invention resides broadly in introducing a liquid or plastic cementitious material possessing magneticproperties or containing finely divided magnetic materials into a portionl of the formation to be cored whereby such introduced mate- Qther objects and features'of novelty will be Ievident hereinafter;

embodiment of the invention, Figure 1 is a partial cross-sectional elevation oi? a core bit and drill collar in the bottom of a well borehole with the pilot drill in operating position therein.`

Figure 2 shows the apparatus of Figure 1 with Vthe injector in position 1n the drin collar.

Figure 3 shows the apparatus'of Figure 1 with the retractable core cutter and core barrel in operating position in the drill collar and core bit.

Figure 4 is an enlarged detailed cross-sectional i elevation of the injector mechanism of Figure 2*.

Figure 5 is an enlarged perspective view of a typical core sample.

Referring to the drawing, l0 is preferablya. three or four bladed core bit head,.and H is a special drill collar, of a well knwntype adapted to operate in conjunction with a retractable type of core barrel, such for example, as a Reed Roller Bit Companys Reed BR. drilling bit with wire lineretractable core barrel. A tool joint box l2 is screwed into the top end of the said drill collar'll and adapted to make connection with the tool joint pin i3 of the supporting drill stem. The'tool joints and drill stem employed herewith are of the full Vhole type. n

In place in the drill collar ii and core bit head it is a pilot bit assembly comprising a pilot bit I6 of relatively small diameter extending below the blades of the core bit head and attached to a pilot bit shank li oi larger diameter which extends upward through the core bit head andis secured at the top at i3 by suitable threads to the lower end of an elongated cylindrical body 2l! which may be a standard retractable core barrel assembly. The said cylinder or core barrel assembly 2@ in turn comprises ahollow barrel 2l having threads i8 at the lower end and an upwardly extending plunger 22 ofreduced diameter at the upper end adapted to slide upwardly through a keyed slip joint 2d into the upper tubular carrier body member 25.k The keyed slip joint is adapted to prevent relative rotation between the plunger 22 and the body member. A spiral spring 2i, acting under compression normally maintains the plunger and In the drawing which illustrates a preferred thus retained ln'place within the drill collar and held against relative rotationjby the action of the said dog latch 29 in the slotted recess and under the compression force of spring. 21. Within the top of the carrier body 25 is a slidable spear head pull-bar 34 having at its top extension a spear head 35 and near its lower end a cross pull-.bar pin 31 which engages at its ends the eliptical openings 39 of the said dog latch 29. An upward pull upon the spear head is transmitted through the slidable pull-bar 34 and pin 31 to the upper sloping surface of the opening 39, thereby causing the dog'29 to pivot counterclockwise about pin 33 and to retract into the carrier body out of contact with the latch slot 32, thus freeing the apparatus to. move upward within the drill collar and drill pipe.

At the bottom end of the core barrel 2|, as stated hereinbefore, are threads I8 to` which the pilot bit shank I1 is attached. In the pilot drilling assembly of Figure 1, the said shank I1 closes the barrel 20 at the lower end so that the barrel performs no other service than to guide and retain the pilot bit in drilling position within the core bit head. The core bit head I is provided with a slush ring 4I which limits the downward movement of the barrel 20 and pilot bit I6 by contacting the pilot bit shank collar 42 which is slightly larger in diameter. are provided in the slush ring to permit drilling fluid to by-pass from the drill collar to the core bit head.

Sufficient clearance is providedl between the pilot drill shank and core head to allow a portion of the drilling fluid to flow therebetween from the drill stem to the cutting surfaces of the said core head. A drilling fluid circulation duct is also provided through the shank I1 and bit I6, the inlet of which is shown at 43 and the outlet of which is shown at 44 adjacent the cutting blades of the pilot bit.

The pilot bit shank I1 is provided, at the lower end at the junction point of the pilot bit, with a pair of sloping blades 45 and 46 to drill in the formation a conical shaped enlarged entrance as shown at 49 to the pilot bore hole 48.

In the lower portion of Figure 2 a retractable cement injector is shown in place in the beforementioned drill collar II and core bit head III. The lower portion of the injector device is also shown in more detail in the enlarged sectional view of Figure 4.

Referring to Figures 2 and 4, the upper portion of the injector 1s identical with that hereinbefore described in connection with the retractable pilot bit mechanism of Figurel. The lower portion of the injector comprises a barrel 50, located in the position occupied by the barrel 2I of Figure 1 ,and adapted to contain charges of ce- Perforations 41 mentitious material 5I and wash liquid 52 therein separated by means of a frangible partition 53, which may consist of a,suitably treated disc of heavy paper, cardboard .or iiberboard. 'I'he upper end of the barrel 50 is closed by and makes a threaded connection with the cylindrical head 54, which forms the lower end of the plunger rod 22. The passageway 55 is provided through the headv 54 through which the drilling uid under pressure in the drill stem and drill collar can gain access to the upper end of the barrel 50 above the cylindrical stop-plug 51. The stop-plug 51 is provided with a leather packing cup 5l at the upper end and a conical packer 59 at the lower end thereof, the said stop-plug being adapted to slide downward through the barrel under drilling uid pressure to the conical seat 55.

coupler 62 is provided a conical seat 65 adapted V to form a duid-tight seal with the beforementioned conical packing 59 on the stop plunger 51.

Extending from the lower screwed connection 6B, of the coupler 62 is the shank 61 of the injector tube 68, and. the shank 61 and-injector tube 68 are provided with central fluid ducts 69 and. 10 respectively leading through the passageway 1I in the coupler 62 from the 'barrel 50. Surrounding the lower endof the barrel 5U a cup-shaped packer 13 is provided and adapted to make a fluid-tight seal between the barrel 50 and the bore -of the drill collar II. .The downward thrust of the spring 21and the weight of the injector is as in the case of the apparatus in Figure l, also supported by means of the olf-set collar portion 14 of the coupler 6 2 upon the slush ring 4I.

Referring now to Figure 3, the core barrel 2I and the apparatus thereaboveis identical to that shown and described for Figure l, which is above and supported by the collar 42 upon the slush ring 4I, but extending below the core barrel 2I and the collar 42 attached -to threaded connection I8 is a core barrel extension 11 having a core catcher 18 therein near the lower end and terminating at the lower end in a standard core cutter as shown at 19.

Figure 5 illustrates the appearance of a short length of a typical core recovered by the apparatus as a result of the exercises of the method of this invention. The section of the core is cylindrical in shape having an external diameter corresponding to that of the core cutter .19, and contains a coaxial cylindrical body of cementitious material as shown at 80, having a diameter equal to that of the pilot bore hole as shown at The operation of the apparatus is as follows:

Assuming that conventional core drilling operations have been in progress and that it is now desired to obtain an oriented core sample, the retractable core bit and core barrel are then withdrawn from the drill stem by means of a wire line operated overshot and the before described mechanism carrying the pilot bit is next dropped into place in the drill collar II where 4it takes the position shown in Figure 1 but with the said drillcollar and core bit I0 raised and suspended above the bottom of the hole a distance sufficient to allow the pilot bit I6 to extend its full length from the core head without touch.- ing the underlying formation to be drilled.l When the said device of Figure 1 has thus fallen into place the dogv 29 will automaticallyvopen under the force of the spring v4I and latch in the recess 32 at the lower oil-set end of the tool joint box4 er end of the pilot bit Il makes contact with the bottom of the drill hole. If the drill pipe I3, drill collar II' and core bit Il are then continuedv to be lowered at a rate greater than the drilling progress made by the pilot bit 15, sumcient upward thrust will be, imposed upon the aaoasas said pilot bit l's to denser, the spiral spring 21 and allow the wholezlower portion of the instrument to move upward into the drill collar against the force thereof. The length ofthe upper body 25 and the spring 21 is preferably made such that the core bit Il can be deliberately lowered will have travelled down the full length of the f barrel 50 `and will come` to restwith the conical 'to the bottom of the bore hole I4, and the pilot I` possible to put more weight upon the pilot bit than that required-to compress the-spring 21 andY thereby eliminating the necessity of carefully gauging the amount of weight placed upon the pilot bit. After the core drill has thus been run to, the bottom of the bore hole and if deslred when the core head rests upon bottom, rotation may be commenced and the pilot bit I6 allowed to drill aheadv inio the underlying Iormation alone under the forcev of the compressed spring 21 without further lowering of the drill pipe .as a Whole. The proper drilling weight on the pilot bit I6 is thusautomatically regulated l which eliminates the possibility o f damaging the pilot bit as would be likely to occur were the pilot bit xed within the core drill and it thus became necessary to gauge the drilling weight applied to the pilot bit from the top of the drill stem.

' When the core drill' il! is being rotated on the bottom and the pilot bit I6 has drilled into the underlying formation to the full length of the extension thereof under the force of the spring 21, the sloping cutter blades 45 and 46 nally come into contact with the formation. cutting a shallow conical depression of enlarged diamp dropped through the drillpipe into the drill' collar Il and core biti to the position shown in Figure 2, whereupon it latches in place in the vmanner hereinbefore described and illustrated in connection with the pil-ot drilling mechanism oi Figure vl. bottom and the injector tube oil ihusinserted in the pilot hole et, pressure is next applied to thev drilling duid in the drill pipe. The packer le surrounding the barrel 50, prevents the dow of the said drilling uid past the injector instrument resulting in a differential pressure around the instrument. The said duid dierential pressure is transmitted to the top of the stop-plug 51 by way of the passage h in the head d@ and the stop-plugl under the force ci the drilling duid is forced downward expelling rst thewash liquid 52 and then the cementitious material 5l by way of the passages du and l@ of the shank 51 and injectortube be into the pilot borehole 58. The volume oi the charges oi wash liquid 'packer 58 upon the conical seat 65 of the coupler 82 thus preventingi'urther'ilov lof -cement .and drilling huid. This will be evidenced by a rise in the drilling iluid pressure at the pumps at the well surface. y. The cementitious charge thus having been injected into the pilot borehole, the injector tube is next withdrawn from the pilot borehole 4 8 by raising the core bit and drill collar off the bottom asuiilcient distance to allow the cementitious, 'material in and surrounding the conical bore 8| to ow back into the space in the pilot borehole y48 evacuated by thev withdrawal of the said injector tube 68. l

The cementitious material in the pilot borehole 48 is then lallowed to remain until set and during this setting period the-injector apparatus is withdrawn from the drill collar by means of the wire line as herein above described in connection with the pilot drilling mechanism.

"Following this a standard retractable'core barrel and core cutter are dropped into thedrill pipe With the core bit l@ resting on the 52 and the cementitious material El' are measf uredand controlled so that the inside suris of the pilot borehole 48 is drst washed by the wash liquid and then expelled from the pilot wborehole and completely pl with the and allowed to come to rest in a position as vshown in Figure 3. The com barrel is then locked into Position in the same manner -as that described in connection with the pilot 'drilling mechanism of Figure 1. Core drilling operations are then continued and coresl taken of the underlying formation containing the vcementitious material which has been allowed to set in the pilot borehole 48. After sullcient, coring has been carried on; the retractable core barrel containing the cores is withdrawn from the drill pipe by means ci" the wire line overshot in the manner hereinbefore described. Sections of the cored formation thus recovered resemble that shown in Figure 5, the outside diameter thereof corresponding to the internal diameter of the core cutter l@ and the central cyiinder of cementltious material u@ cori-ending in diameter to that of the pilot borehole i8. I l' The injector device oi re 4 described hereinbefore, particularly barrel do, coupling e2, and

shank and tube @l and d respectively. are pre-, erably constructed oi a non-magnetic metal auch.

check valve ed may comprise any suitable liu` uid prefebly adapted to deocculate the drilllng mud and to thus cause the removal of a substantial portion of the mud cake formed on the walls of said pilot borehole and at the same time to f r the same from the pilot borehole in order to prepare the formation wall surfaces thereof for a d bond with the subsequently in- Jected cement'itlous material. Suitable wash liq.`

uids for this puropse which may be ployed are:

-water.- sodium tetraphosphate, sodium bicarbonate. sodium carbonate, calcium chloride, hydrochloric acid and the like agents ada to remove the mud cake formed on the pilot borehole walls during drilling.

7s Cementitious material. having magnetic properties and which is suitable to be injected into the borehole and the charge of which is shown in place in the injector barrel 50, between the frangible partition 53 and the stop-plug 51, may comprise a quick-setting Portland cement or the like containing finely divided ferromagnetic particles mixed therewith or in suspension therein. Other cementitious materials which may be similarly employed are plaster of Paris, magnesiumoxychloride, and the like.. Such ferromagnetic particles contained in the cement may comprise finely graded iron or steel filings, nely divided permalloy or other suitable highly ferromagnetic alloys or powdered magnetic iron oxide.

The ilnal magnetie polar determinations of formation core samples processed and recovered in accordance with the hereinbefore described method may be determined in accordance with well known testmethods, for example, the teachings ofthe patents tov Herrick, 1,792,391, and Hering et al. 2,105,650.

'I'he foregoing is merely illustrative of'a preferred method and embodiment of the invention and is not to be considered limiting since many variations may be made by those skilled in the art within the scope of the appended claims.

I claim:

1. A method of imparting magnetic properties to formation core samples comprising the steps of drilling a borehole to the formation to be cored, drilling a pilot hole of smaller diameter than the core to be taken at the end of said borehole, positively displacing drilling mud from said pilot hole by positively injecting a wash liquid thereinto, positively displacing said wash liquid from said pilot hole by positively injecting a magnetic cementitious material thereinto and allowing it to remain undisturbed until set, and coring ahead and removing a core sample ofsaid formation containing a portion of said inlected magnetic cementitious material.

2. Apparatus for imparting magnetic properties to formation core samples comprising in combination,` means to drill a borehole to the formation to be cored, means to drill a pilot hole of smaller diameter than the core to be taken at the end of said borehole, means adapted to be introduced into the pilot hole to inject fluent, magnetic material into said pilot hole, means to cut a core sample from said formation concentric with and including a portion of said pilot hole, and means to recover said core sample from said bore hole. l

3. Apparatus for imparting magnetic properties to formation core samples comprising in combination, means -to drill a-borehole to the formation to be cored, means to drill a pilot hole of smaller diameter than the core to be taken at the end of said borehole, means to positively displace drilling iiuid from the said pilot hole, means to -inject'a cementitious material positively. thereinto, and means to cut and recover a core sample from said formation containing a portion of said pilot hole and its cemented contents.

4. Apparatus according to claim 2 in which the means to drill said pilot hole comprises a pilot bit retractable through the core drill and the drill stem.

5. Apparatus according to claim 2 in which the means to inject magneticl material into the pilot hole comprises a barrel adapted to contain a charge of fluid or plastic material and adapted to be lowered into the borehole, a tubular extension on the lower end of said barrel and adapted to extend into the pilot hole, and means to forcibly expel the contents of said barrel through said tubular extension and into said pilot hole.

6. Apparatus for imparting magnetic properties to formation core samples comprising in combination, means to drill a bore hole to the formation to. be cored, means to drill a pilot hole of smaller diameter than the core to be taken at the end of said borehole. means to inject a cementitious material into said' bore hole, and means to cut and recover a core sample from said formation containing at least a portion of the cemented contents in said bore hole, said means to inject cementitious material into the pilot hole comprising a barrel adapted to contain a charge of fluid or plastic material and adapted to be lowered into a retractable core barrel type of drill collar, a tubular extension on the lower end of said barrel and adapted to extend through the core bit and into the pilot hole and means to forcibly expel the contents of said barrel through said tube and into said pilot hole.

PHILIP H. JONES.' 

